1. Field of the Invention
The present invention relates to a droplet spraying and applying head module, a droplet spraying and applying apparatus, and a method of manufacturing a coated body. In particular, the present invention relates to: a droplet spraying and applying head module used for manufacturing a coated body such as a liquid crystal display panel or an organic electroluminescence (EL) display panel; a droplet spraying and applying apparatus including this droplet spraying and applying head module; and a method of manufacturing a coated body by using this droplet spraying and applying apparatus.
2. Description of the Prior Art
As described in Japanese Unexamined Patent Publication No. 2004-31070, a droplet spraying and applying apparatus is known which is used for manufacturing an organic EL display panel.
In this droplet spraying and applying apparatus, liquid made by dissolving coloring matter such as polymer luminescent material in a solvent is sprayed as droplets through nozzles of a droplet spraying and applying head, and the sprayed droplets are applied to a substrate surface. Then, by evaporating the solvent in the droplets applied to the substrate surface, a film formed of the coloring matter remains on the substrate. Thus, an organic EL display panel is manufactured.
In such a droplet spraying and applying apparatus, there are some cases of using a droplet spraying and applying head module 100 such as shown in FIG. 6.
This droplet spraying and applying head module 100 includes a droplet spraying and applying head 101, a buffer tank 102, and an apparatus fixation portion 103. The droplet spraying and applying head 101 and the apparatus fixation portion 103 are screwed to each other, and the droplet spraying and applying head 101 and the buffer tank 102 are connected to each other with a flexible supply pipe 104.
The droplet spraying and applying head 101 includes a casing 105 and a nozzle plate 106 fixed to one side of the casing 105. In the casing 105, a plurality of liquid chambers (not shown) are formed, and a plurality of piezoelectric elements (not shown) are provided corresponding to the respective liquid chambers. In the nozzle plate 106, a nozzle (not shown) is formed for each liquid chamber.
The buffer tank 102 contains liquid (e.g., ink) made by dissolving coloring matter in a solvent. This liquid is supplied through the supply pipe 104 to the liquid chambers in the casing 105. A main tank (not shown) is connected to the buffer tank 102, and the buffer tank 102 is replenished with the liquid from the main tank.
In the case where the droplet spraying and applying head module 100 is attached to the droplet spraying and applying apparatus, before this attachment, the liquid is filled into the droplet spraying and applying head module 100. In the case where the liquid is filled into the droplet spraying and applying head module 100, bubbles are prone to enter the liquid chambers and the nozzles. The bubbles which have entered therein need to be removed.
Accordingly, in order to remove these bubbles, the work of filling liquid into the droplet spraying and applying head module 100 is performed with the droplet spraying and applying head module 100 attached to a filling jig. In the droplet spraying and applying head module 100 attached to the filling jig, the buffer tank 102 is fixed in place, and the droplet spraying and applying head 101 can rotate in a vertical plane.
After the liquid is filled into the droplet spraying and applying head module 100 attached to the filling jig, the droplet spraying and applying head 101 is rotated in the vertical plane. This rotation moves bubbles existing in the liquid chambers and the nozzles toward an exhaust port 107 provided in such a way that the exhaust port 107 is connected to the liquid chambers. By opening the exhaust port 107, the bubbles are expelled outside the droplet spraying and applying head 101.
Thus the flexible supply pipe 104 connecting the droplet spraying and applying head 101 to the buffer tank 102 has a length enough not to cause any problem even when the droplet spraying and applying head 101 is rotated in the vertical plane.
After the droplet spraying and applying head 101 attached to the filling jig is rotated and the bubbles are expelled through the exhaust port 107, a purging process for causing liquid to flow out through the nozzles is performed. In this purging process, the droplet spraying and applying head 101 is rotated to a position where the nozzles point upward, and a pressure is applied to the inside of the buffer tank 102, thereby causing liquid to flow out through the nozzles. In the case where the bubbles remain in the liquid chambers and the nozzles, this purging process expels the bubbles together with the liquid through the nozzles.
After the process of expelling the bubbles through the exhaust port 107 by rotating the droplet spraying and applying head 101, and the purging process for causing the liquid to flow out through the nozzles are finished, the droplet spraying and applying head module 100 is detached from the filling jig, and then is attached to the droplet spraying and applying apparatus.
After the bubble expelling process and the purging process are finished, no bubbles exist in the liquid filled in the droplet spraying and applying head module 100. Accordingly, droplets can be sprayed through the nozzles of the droplet spraying and applying head 101 without causing failure of spray or defective spray. The droplet spraying and applying head 101 is part of the droplet spraying and applying head module 100 attached to the droplet spraying and applying apparatus.
However, in the above-described droplet spraying and applying head module 100 and the droplet spraying and applying apparatus employing this droplet spraying and applying head module, no consideration is given to the following points.
When the droplet spraying and applying head module 100 is attached to or detached from the filling jig or when the droplet spraying and applying head module 100 is attached to the droplet spraying and applying apparatus, the droplet spraying and applying head 101 and the buffer tank 102 are individually attached or detached. This requires a lot of labor.
Moreover, since the supply pipe 104 connecting the droplet spraying and applying head 101 to the buffer tank 102 is long, the supply pipe 104 is prone to hit against the other members during the work of detaching the droplet spraying and applying head module 100 from the filling jig and of attaching the droplet spraying and applying head module 100 to the droplet spraying and applying apparatus. If the supply pipe 104 hits against the other members during this work, pressure fluctuation occurs in liquid in the droplet spraying and applying head module 100 due to the hit. There are some cases where gas is sucked in through the tips of the nozzles due to this pressure fluctuation. The sucked-in gas causes failure of spray or defective spray of droplets through the nozzles.